First AR10 build, what did I do wrong?

[RTELF]

Finally put together the ar10 parts I had lying around and it work great once I got the gas block adjusted but then it started having issues ejecting and seemed to really chew up the rims.

I know the AR10 ejectors are normally pretty rough on the brass but I just want confirmation on what I've gathered from forum browsing.

Based off what I've seen it probably wasn't gassed properly, or the buffer weight was off, but weighing more towards improper gassing

This was running it with empty casings just to test cycling, work work fine then every couple rounds it would either fail to fully pick up a round which is probably cause it doesn't have a bullet or fail to fully go into battery

 

[BCP]

Parts list?

 

[RTELF]

Parts list?

Oh yeah sorry, totally forgot that
Aero M5 prebuilt lower
Aero M5E1 enhanced upper
Faxxon bcg and 20" barrel
Suparms adjustable gas block

 

[bfoosh006]

Finally put together the ar10 parts I had lying around and it work great once I got the gas block adjusted but then it started having issues ejecting and seemed to really chew up the rims.

I know the AR10 ejectors are normally pretty rough on the brass but I just want confirmation on what I've gathered from forum browsing.

Based off what I've seen it probably wasn't gassed properly, or the buffer weight was off, but weighing more towards improper gassing
View attachment 8503977View attachment 8503978View attachment 8503979


This was running it with empty casings just to test cycling, work work fine then every couple rounds it would either fail to fully pick up a round which is probably cause it doesn't have a bullet or fail to fully go into battery
View attachment 8503980View attachment 8503983

I would round / smooth / polish the edges of the ejector.

Clean out whatever that sliver is in the bolts FP aperture hole.

Polish the feed ramps.

Rifle lower w/ 5.6oz buffer ? Carbine lower w/ 3.8oz buffer ? ... any way, the OEM buffer weights on both are what I would consider LtWt,
For that matter, even the recoil spring might be as cheap as Aero spec'd. ( I use a Tubbs 308 Flatwire in all my LFAR's.... YMMV )

Ummm... yeah don't cycle fired cases... the necks will be to large to seat easily... and .. , well you can see the rest.

How many rounds through it so far ? IMHO, LFAR's need about 100+ ish rounds fired in a well lubed rifle for break in.

And I assume you thoroughly cleaned the chamber, etc ? ( removing any packing oils )

How did you adjust the Adj. GB ?

And FWIW... as to what did you do wrong ? .. Nothing, lots of LFAR's benefit from tuning and fussing.

 

[NCgreentick]

With a Faxon barrel, you need the "AR10" length gas tube, not just any rifle length. It is about 3/8 longer than standard rifle. I bought mine from Wilson Combat but I see they are OOS.
Disregard if you already know this.

 

[Punkur67]

I had the same issue. It ended up being the aero bolt. I swapped the bolt for a JP and never had the issue again

 

[BCP]

Don’t cycle empty cases

My guess would be sharp edges on ejector/extractor/rough bolt face combined with gassing issues

I don’t know what ammo you are shooting but regular 150gr fmj stuff might be an idea for testing

 

[mudholestomper]

That ejector should have a slight bezel on it. It clearly doesn’t. That’s gouging into the brass.

I don’t understand what you hoped to accomplish by cycling fired brass.

As far as the gassing goes, I would run it wide open until you’ve put 100-150 rounds through it. It takes a bit of shooting to smooth things out in my experience.

Then you can start dialing it back, shooting one round at a time and checking that it locks back on an empty mag.

As has been mentioned, a JP bolt is the way to go. You’ll be impressed with how much better the quality is over your Aero bolt.

 

[AZgeek]

Yup. JP full mass carrier and high pressure bolt/firing pin functions flawlessly in my build

 

[RTELF]

Aight thanks for the input everyone, I'll probably buy a JP bolt + SCS in the future. Gotta check gas tube length, was going off recommendations from a buddy of mine but I wouldn't be surprised if it was the wrong length.

All the debris in and around the bolt is lil brass shavings, I pretty thoroughly cleaned and re-lubed everything when I put it together but it'll get another round of that given how much debris there is.

As for how many rounds have been put through the gun, I'd say around 60-80 or so, and the only reason I was cycling empties was because I read it on here somewhere.

PS: I should add that it's a faxxon bolt not aero, I just didn't separate it from the barrel on the build list for some reason

 

[RTELF]

I would round / smooth / polish the edges of the ejector.

Clean out whatever that sliver is in the bolts FP aperture hole.

Polish the feed ramps.

Rifle lower w/ 5.6oz buffer ? Carbine lower w/ 3.8oz buffer ? ... any way, the OEM buffer weights on both are what I would consider LtWt,
For that matter, even the recoil spring might be as cheap as Aero spec'd. ( I use a Tubbs 308 Flatwire in all my LFAR's.... YMMV )

Ummm... yeah don't cycle fired cases... the necks will be to large to seat easily... and .. , well you can see the rest.

How many rounds through it so far ? IMHO, LFAR's need about 100+ ish rounds fired in a well lubed rifle for break in.

And I assume you thoroughly cleaned the chamber, etc ? ( removing any packing oils )

How did you adjust the Adj. GB ?

And FWIW... as to what did you do wrong ? .. Nothing, lots of LFAR's benefit from tuning and fussing.

Where exactly would you round off the ejector?

 

[bfoosh006]

Where exactly would you round off the ejector?

Post # 1.... https://www.ar15.com/forums/Precisi...woods-Guide-to-the-Ultimate-AR-fixed-/4-6919/

 

[Cascade Hemi]

Worked before but now it doesn't? Looks like high pressure. If you shut off the gas and you still have flat primers and ejector imprints, you probably have carbon in the throat. If it's a Faxxon nitrided barrel, they leave a rough layer down the bore that needs to be cleaned out with an abrasive like iosso.

 

[Bevo]

JP bolt.
XH buffer + .308 spring

 

[45-90]

Probably has Nothing is probably wrong with the parts.
Do not need high dollar bolts, most come from the same few manufacturers, made on CNC machines, out of the same 2 alloys of steel with the same heat treat and inspection....and both alloys work well.
Can't tell much from pictures.
The barrel extension has sharp corners, polish them.
Adjustable gas block, a SA. Did you follow instructions? That sat .025" off the journal shoulder.
Adjust the gas block properly for the ammo your shooting.
Did you turn down the gas block and open it a few clicks at a time...shoot one at a time and open the gas block until the bolt locked back? And notice where the ejection pattern is.

Don't be concerned about feeding empty cases....the ones you'll use, will have bullets in them, and the ones that need to feed, and be concerned about.

Have someone who has built alot of ARs go over your build with you.